Means for nullifying inductive interference between parallel circuits.



No. 851,856. PATENTED APR. 30, 1907.

E. BLAKENEY. v MEANS FOR NU-LLIFYING INDUCTIVE INTERFERENCE-BETWEEN PARALLEL CIRCUITS.

APPLICATION FILED JAN. 7, 1907 .rnr mmms P575125 co., wnsnmawn, :74 c.

UNITED STATES PATENT OFFICE.

EDWARD BLAKENEY, OF OSSINING, NEW YORK, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

MEANS FOR NULLIFYING INDUCTIVE INTERFERENCE BETWEEN PARALLEL CIRCUITS.

Specification of Letters Patent. Application filed January '7, 1907. fierial No. 351,245.

No. 851,856. Patented April 30, 1907.

To all whom it may con ern: their opposite poles to line. The trans- Be it known that I, EDWARD BLAKENEY, mitters may be actuated by keys K. To residing at Ossining, in the county of WVestthis extent the system is well known. chester and State of New York, have invent- In operation, for each depression and re- 5 ed certain Improvements in Means for Nullilease of a key the current traversing the line ing Inductive Interference Between Paris reversed, and at this time a momentary allel Oircuits,of which the following is a speciinduced eleetromotive force will manifest 6o fication. itself throughout the adjacent line tending to This invention has for its principal object distort signaling currents which may be flow- IO the prevention of inductive disturbances in ing therein. This is felt in both the relay of signaling circuits, and is especially concerned the associated home station, from the comwith the nullifying or neutralizing of that panion station of which the disturbing curmutual action between muliplex telegraph rent starts, and in that of the distant station. systems which is manifested in the receiving For the mutilation of signals of the home re 15 instrument at a distant station. lay of the affected line by the outgoing in- It consists in a novel method of and means duced impulses a remedy has already been for accomplishing this result, wherein a porproposed and found fairly satisfactory. tion of the inducing current in one circuit is This consists in connecting between the articaused to act upon an instrument in an adficial lines of each pair of stations A B and 20 jacent circuit to neutralize the effect of the A B a bridge conductor 13 including a coninduced current. denser c and a non-inductive resistance 1".

In the accompanying diagrammatic repre- By this means the impulse induced in the sentation of a system adapted for the carrymain line is balanced by a similar impulse ing out of the invention, L, L represent communicated through the bridge 13 to the 25 telegraph lines which are so closely adjacent artificial line, these balancing one another in that current changes in one will induce curthe bridge 10 and producing no effect upon the rentsinthe other. They might, for example, relay. Such an arrangement, however, has consist of a pair of conductors included in a noiniluence upon the incoming induced cur-- cable, each of said conductors being inderent, since the operation of this duplex is 30 pendently employed as a telegraph line. dependent upon a diii'erence of potential for The lines L and L have terminal stations A incoming currents at the extremities of the A andB B respectively, which are arranged bridge 10 and so far as is known to me the in pairs A, B and A B with the stations of problem of neutralizing disturbanceslin the overeach pair situated in comparative proximity. Each line is shown as arranged for multi lex transmission, the particular system illustrated being a polar bridge duplex. This is too well understood to require specific description. It may be briefly said that at each station is a receiving instrument or relay, those at the stations A, B, A and B be ing respectively designated by the characters R, R R and B. Each relay is polarized and has its operating coils a included in a conductor 10 bridged between the main line and a suitable artificial line 1, said lines forming two arms of a WVheatstone balance, While conductors 11 and 12 containing the usual resistances, furnish the other two arms. These conductors 11 and 12 are joined to one another-and connected to earth through the contacts of a transmitting apparatus T, and sources of electrical energy D D having distant relay has not been solved. come this di'lliculty by causing a proper portion of the inducing current to act upon the affected relay in a dill'crent manner or oppositely from the action of the induced current thereon. To this end there is connected in parallel with each of the bridges 10 a conductor 14 which contains coils b for the relay of the companion line these coils I) being wound differentially from the main coils a, or so that the inducing and induced currents ilow about the cores of the relays in opposite directions. In each of the conductors 14 is a condenser 0*, preferably of variable capacity, and each bridge 10 contains a preferably adjustable inductive resistance 1".

It will be seen that the current flowing into a distant station, A for example, after the depression of the key at A, will be divided between the operating winding a of the relay R in its own line L and winding 1) of the companion relay R As this current in the coil b acts oppositely upon the second relay R from the current induced in the line L by the variation of current in the line L and passing through its operating winding a, the effect of the induced current will be nullified, if the impulses are equal in strength and duration, and coincide in time. By varying the resistance r more or less current may be forced through the conductor 14, and providing a suitable capacity at c the correcting pulse will be momentary, as is that induced. That is, the intensity and rate of application of the correcting pulse is thus controlled. Moreover, these impulses pass through the coil at practically the same instant, thus the induced current is neutralized and the incoming signals are undisturbed. On the other hand the outgoing signals will not influence the corrected relay, since for them the junctures of the conductors 10 and 14 are at equal potential, a condition essential to the operativeness of the telegraph system. Their inducing effect will be compensated for by the bridge 13, as has been already described.

I claim:

1. The method of nullifying inductive disturbance of one telegraph line upon a receiving instrument located in another line at a point distant from the point of transmission of an inducing current in the first-mentioned line, consisting in causing said inducing cur rent in the first line to act u on said receiving instrument in the second line in a difierent manner from the induced current in said second line.

2. The method of nullifying inductive disturbances between signaling conductors, said disturbances arising from the operation of a transmitting instrument at one station and affecting a receiving instrument at a distant station, which consists in causing the inducing current in one conductor to act upon the distant receiving instrument of another conductor in the opposite direction from the induced current in said distant instrument.

the neutralizing ,7 ing lines each having a receiving instrument,

of a winding located upon a receiving instrument and being connected only with a companion line, and means for causing the current flowing through said winding from the companion line to act momentarily upon the receiving instrument.

6. A telegraph system comprising a plurality of adjacent lines each provided with terminal stations, receiving instruments situated at the stations and each having an operating winding included in the line to which it belongs, and a second winding for each receiving instrument independent of its operating winding and being connected with another of the lines.

7. A telegraph system comprising a plurality of adjacent lines each provided with ter minal stations, receiving instruments situated at the stations and each having an operating winding included in the line to which it belongs, a second winding for each receiving instrument independent of its operating winding and being connected with another of the lines, and condensers included in the connections of the second windings, substantially as described.

8. A multiplex telegraph system comprising adjacent main lines provided with terminal stations, an artificial line associated with each main line at each terminal station, a receiving instrument bridged between each artificial line and its main line, and means for applying to each receiving instrument a portion of the current flowing from the distant station of a companion line.

9. A multiplex telegraph system comprising adjacent main lines provided with terminal stations, an artificial line associated with each main line at each terminal station, a receiving instrument bridged between each artificial line and its main line, means for applying to each receiving instrument a portion of the current flowing from the distant station of a companion line, and means for controlling the rate of application of said current.

10. A multiplex telegraph system compris- 3. The method of neutralizing the effect of ing adjacent main lines provided with termutual induction between two multiplex telegraph lines manifested in their receiving instruments which are distant from the point of transmission of an inducing current, consisting in dividing the inducing current part to said distant receiving instrument of one line and part to said distant receiving instrument of the other line, and causing said current to act differentially upon said instruments.

4. The combination with adjacent signaling lines each having a receiving instrument, of a winding located upon a receiving instrument, and being connected only with a companion line.

5. The combination with adjacent signalminal stations, an artificial line associated with each mainline at each terminal station, a receiving instrument bridged between each artificial line and its main line, and a conductor connected in parallel with the bridged receiver and including a coil upon the receiving instrument at the same end of a companion line, as and for the purpose set forth.

1 1. A multiplex telegraph system comprising adjacent main lines provided with terminal stations, an artificial line associated with each main line at each terminal station, a receiving instrument bridged between each artificial line and its main line, a conductor connected in parallel with the bridged receiver and including a coil upon the receiving instrument at the same end of a companion line, and means for varying the distribution of current between the parallel conductors.

12. In a duplex telegraph system the combination with two main lines so situated that they may act inductively upon one another and being provided with stations arranged in pairs, said pairs including a station of each line in comparative proximity to one another, an artificial line at each station, a bridge conductor connecting each artificial line with its main line, a relay having a coil connected in the bridge, a conductor connected to the main and artificial lines in parallel with the bridge conductor, and a differential coil upon each relay in- 

